shadow(3) - perldoc - phpman

Found in /usr/share/perl/5.34/pod/perlfaq8.pod
  How do I modify the shadow password file on a Unix system?
    If perl was installed correctly and your shadow library was written
    properly, the "getpw*()" functions described in perlfunc should in
    theory provide (read-only) access to entries in the shadow password
    file. To change the file, make a new shadow password file (the format
    varies from system to system--see passwd(1) for specifics) and use
    pwd_mkdb(8) to install it (see pwd_mkdb(8) for more details).